Helical knife apparatus for cutting a continuous filament bundle into staple fibers of uniform length



Nov. 16, 1954 D HULL 2,694,447

HELICAL KNIFE APPARATUS FOR CUTTING A CONTINUOUS FILAMENT BUNDLE INTO STAPLE FIBERS OF UNIFORM LENGTH Filed Aug. 16, 1952 3 Sheets-Sheet l INVENTOR DONA LD R. HULL ATTORNEY NOV. 16, 1954 D R U 2,694,447

HELICAL KNIFE APPARATUS FOR CUTTING A CONTINUOUS FILAMENT BUNDLE INTO STAPLE FIBERS 0F UNIFORM LENGTH O Filed Aug. 16, 1952 5 Sheets-Sheet 2 INVENTOR DONALD R. HULL ATTORNEY Nov. 16, '1954 HULL HELICAL KNIFE APPARATUS FOR CUTTING A CONTINUOUS FILAMENT BUNDLE INTO STAPLE FIBERS OF UNIFORM LENGTH Filed Aug. 16, 1952 3 Sheets-Sheet 5 R Y L m L m w u m w w w A Z N 0 D Y B y mm mm Q& Q

United States Patent Q HELICAL KNIFE APPARATUS FOR CUTTING A CONTINUOUS FILAMENT BUNDLE INTO STAPLE FIBERS F UNIFORM LENGTH Donald R. Hull, Seaford, DeL, assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application August 16, 1952, Serial No. 304,712

7 Claims. (Cl. 16461) This invention relates to apparatus for cutting elongated objects, such as ropes, rods or tubes, into uniform lengths, and is particularly concerned with apparatus for cutting bundles or tows of substantially continuous filaments into staple fiber of uniform length.

Artificial fibers are spun in continuous lengths, whereas most natural fibers are produced in short lengths. In order to blend the two types of fibers it is necessary to cut the artificial fibers into corresponding short lengths or staple. Also, staple is frequently desirable so that the artificial fibers can be processed like wool or cotton, and so that similar effects can be achieved in the products. Various devices have been used to cut continuous filaments into staple. These have all had disadvantages, especially when applied to cutting strong, tough polyamide or polyester fibers.

One type of prior art cutter will be referred to as a centrifugally fed cutter. The bundle of fibers is fed into the center of a device which is rotating at high speed. Passing outward under centrifugal force, the fibers are whirled at high speed against a stationary cutting edge. It has been found that the twisting action on the fiber bundle causes the outside fibers to be cut into longer lengths than the inside fibers. This becomes serious as the size of the bundle is increased. Another type of cutter is the flying knife cutter. Here the problem is to feed the fiber bundle at uniform speed in proper synchronism with the moving knife. With both of the above types the impact between the fiber bundle and the cutting edge produces rapid wear; this is particularly objectionable when cutting tough, highly delustered fibers.

Another type of cutter utilizes the slicing action of a helical knife cutter. Since there is no impact between the fibers and the cutting edge, and the cutting action is distributed over a considerable length of the cutting edge, wear is greatly reduced. Furthermore, the fiber bundle is positively fed to the knife and held While it is cut, so greater uniformity of staple length should be possible. Nevertheless, the helical knife cutter has not been used to any extent in this industry. The manner of gripping the fiber bundle between two wheels or cylinders has not been sufficiently firm to prevent slippage of the inner fibers, particularly when cutting large bundles, resulting in uneven lengths of staple. Also the fibers are fed around a. curve so that the fibers nearest the circumferences of the feed wheels travel through a longer arc and are cut into longer lengths than the fibers nearer the axes of the wheels.

It is an object of the present invention to provide an industrially practical staple cutter of the helical knife type. A further object is to provide such a cutter which will efiiciently cut a large bundle of continuous filaments into staple fiber of uniform length. Other objects will become apparent from the following description, the drawings, and the claims.

These objects are accomplished with an apparatus which comprises a conveyor belt for feeding a filament bundle or tow to a cutter, a plurality of filament clamping members for holding the bundle mounted at uniform intervals along the belt, a rotatable cutter having a helical cutting edge adapted to pass between said clamping members and sever a filament bundle held by the clamping members, driving means for advancing the belt and rotating the cutter in synchronism, and clamp-actuating means for closing the clamping members on the filament bundle and for opening the clamping members to release the cut staple.

In the drawings, which illustrate a preferred embodiment of the invention,

Figure l is a plan view of an apparatus in accordance with this invention,

Filgure 2 is an end viewof the apparatus shown in Figure Figure 3 is a side elevation of the apparatus Wlul certain of the parts removed to show the conveyor belt and clamping members,

Figure 4 is a detailed plan view of one of the clamping members shown in the above figures,

Figure 5 is a cross-sectional elevation of the clamping member taken on the line 5-5 of Figure 4, and

Figure 6 is a perspective detail showing how the helical knife cutter and clamping members cooperate in cutting a tow.

Referring to Figure 1, electric motor 10 provides me driving power for the apparatus. Motor pulley 11, operating through belt 12, turns pulley 13 on drive shaft 14. Shaft 14, through speed reducer 15, drives shaft 16 which transmits power to conveyor belt shaft 17. The ends of shafts 16 and 17 are united through flexible coupling 18. Drive shaft 14 also supplies power to the cutting mechanism through a second speed reducer 20, which is coupled to drive shaft 14 by flexible coupling 21 and shaft 22. The output shaft 23 of this speed reducer engages cutter shaft 25 through flexible coupling 26.

Conveyor belt shaft 17 is supported at the ends by bearings 30 and 31. Mounted on the shaft are drive sprocket wheels 32 and 33 which support and drive continuous link belts 34 and 35, respectively. The link belts comprise the conveyor belt for feeding the bundle of filaments to the cutter. They also run over idler sprocket wheels 36 and 37 which support the belts so that they run through a horizontal path from the drive sprocket wheels. The idler sprockets are mounted on shaft 38 which turns in bearings 39 and 40. These belts support clamping members for holding the filament bundle. For the purposes of clarity only two such clamping members 41 and 42 are shown in Figure l, in positions at the extreme ends of the travel of the belts. In Figure 2 the clamping members 43 and 44 are shown at top and bottom positions, respectively. Actually these clamping members are mounted at closely spaced intervals all the way along the belts as shown in Figure 3. These clamping members are identical in construction.

The construction of an individual clamping member is shown in Figures 4 and 5. The clamping member comprises a hollow frame member 50 which is bolted to the link belts by means of angle irons 51 and 52. Frame member 50 slides on surfaces 53 and 54 over a guide track 55, best seen in Figure 2, which conforms to the path of the belts. A groove 56 is cut into the track to receive roller 57, mounted on the clamp frame to prevent longitudinal displacement. A slotted frame extension 60 is arranged at one end of frame 50 and is cut out to form a stationary jaw 61. A spring-loaded finger member 62 slides back and forth in the slot of frame member 50, being urged in one direction by spring 63. One end of sliding member 62 is cut into a movable jaw 64 arranged to cooperate with stationary jaw 61, and the other end of the member is provided with a cam roller 65 for pulling the member back against the action of the spring. This cam roller rides against cam surface 66, as shown in Figure 2. During the upper horizontal pass of the clamping member the cam surface is shaped to permit the spring 63 to push the sliding member 62 to the left as seen at the top in Figure 2. But, as the clamping member travels around shaft 17 at one end of its path, the cam surface causes the cam follower or roller 65 to move to the right and pull the member 62 to the position shown at the bottom of Figure 2 and in solid lines in Figure 5. The member 62 remains in this position until it has completed its lower horizontal travel and passed around shaft 38, as is evident from the position shown at the bottom of Figure 1.

A filament bundle, indicated by 70 in Figure 5, is laid in the jaws of the clamping member as the member starts on its upper horizontal path of travel. The jaws are open to their fullest extent at this point as shown in Figure 5. The cam surface then releases the roller 65 and the filament bundle is gripped between the V-shaped portions of the jaws under pressure of the spring 63. The position of the'jaws'is then 'as shown'at43 in'"Figure' 2. The"spring'" closing makes it possible for the clamping member to grip a variety of bundle sizes securely. After the filaments are cut the cam action operates to open the jaws and -rele'ase 5 the bundle. The surfaces of the jawsvno'w bearing against the bundle slope outward to positivelyexpel the *bu'ndle. This shape provides a self-cleaning featureg as'will' be ap-" parent from Figure 5.

The cutting mechanism shown in Figures 1 and 2 com prises a helical cutter- 71 m0un=ted-in=head 72 oncutter shaft 25.. This shaft is suitably driven =as previouslyde-- scribed and is supported on each side of -the cutt'er head by .bearings'73 and '74." A cover-75 surrounds the cutter except at the bottom. Thecutter'head-"may suitably be '15 constructed-of a number ofsleevesmachined to 'thesdesired helix angle and adapted to be boltedin proper'posi-"-' tionlto hold the cutter. =-Th cut-ter maybebuilt 'up of-a series-of annular disk blad'es made discontinuousby a radial cut. Alternate sleeves and blades are then assent- '20 bled on the head and bolted together to form a-continuous multiple-turn helical cutter. The -'blades*areground" to provide a cutterof gradually increasing radius-as shown in Figure 1. The cutter is supported-with shaft directly over and parallel to the pathof the filament'bundle' so that 25 the first portion of the cutting edgebarely touches the bun-* dle and the last portion of the-edge cuts=completely through the bundle.

The cutter must cooperate-with= the clamping mem' bers so that the blades extend:betweenthem androtate at a rate which will keep each portion of the' bladesdoing the cutting midway between adjacent 'clamping members. This action is shown in'Figure-6. -The fila' ment bundle 70 has been engaged-by the clamping member 43 and is being conveyedto the left toward '35 the cutter 71. The cutting edges of the cutter are-- spaced apart at a distance equal to the length of staple desired and slice through'the bundleto gradually-increasing depths as the cutter-is revolved-by :the rotationof shaft 25. The clamping members arespaceda corresponding distance apart and are moved-tothe left at the proper rate to remainmidwaybetween. cutting edges; i. e., so that a clamping member willre'main at the same distance'from the adjacent operating portion -.of the*re-'- volving cutting edge.

By the time the filaments have passed beyond-the cutter' they have been cut into bundles of-staple-=which are-- still held bythe clamping-members as showni The-cam now begins-to operate and the clamping jaws'gradually open. When the end of the travel isreached -the jaws- :70 have opened and the staple' is "dumped? The clam'ping members are continuously returned-to the'original posi-* tion. to grip the filament bundles and repeat thecycle as described.

The multiple-turn helical cutter has been shown and 5 5 described, but usually a one-turn helic'al cutter 'blade canbe used satisfactorily. Preferabl-y the: cutter-blade increases gradually I in radius, asdis'closed togradually" slice through the filaments-and -thereby"distribute=the work along the lengthof the cutting edgeb However; '60 a similar result-may be achieved in a-less' satisfactory:' manner with bladesof uniformradius by mounting'the: cutter shaft -25 at a slight"=angle to-*the' tr'avelling' fila'iments, instead of parallel a's shown: 1 Wheii'assembling" the cutter, cracking of the -'knife-' blades canbe" avoided* 05 bY-Pr0vidingthem with radial*slots-'-whichfincrease in length as the radius increases.---- In'this way a one turn" blade can be made sufficiently'flexibleto pullout'to'any lead up to 5 inches without prefortning. I

The required synchronismbetweenthe rotation of theii'70 cutter and the movement of -the'clamping 'members'is obtained by the speed reducers '15 and 20 discussed in" connection with thedriving mechanism.- -A-give'n -cut ting unit may be converted-to cut 'lengths"-which"'are" multiples of the spacing of the 1 clamping members: by' 7 5 using cutters having-a pitch of- 2; 3 or-moretimes't-hat-i shown. Thecuts will then includea corresponding? number of clamping members: between cutsinstead of a" out being made between-each'clampingmember: For" other staple lengths both the pitch of the cutte1""and'the 80 spacing of the clamping members will "needtobe: changed. Proper synchronization of the two will; .of course, be obtained by changesin the speed' reducersi:

as necessary.

The cut staple may be 'rernoved'from"theinachineby' any conventional means, such as a gravity chute or a suctio'n'duct located at the point of release by 'the' clamping members. Removal of imaterial from the members can be facilitated if necessary by an auxiliary jet of fluid or by mechanical means such as a moving rubber-bladed paddle, a rotating rubber disk--or a bristled disk, so arranged..as .to dislodge-the material when the clampingjaws open;

The helicalicuttingapparatusot? this invention is of particular'value 'in' assuring'uniform lengths of staple. It is well known in the art that the' presence-oflengths'l A" or more longer: than the normal length is detrimental to thequality of the yarn spun, especially-whenprocessing on the cotton system, and the greater the difference between the long cutsand the short cuts, the greater becomes the bad effect. The bad effect shows up as nonuniformity in the fiber "roving and-yarn but chiefly as ends broken down in spinning or as cockles (very thick places of 'high'twist) in the!yarn.-'- Results-showin'gthe marked-- improvement obtained by using the heli'calcut ting-apparatus of this invention is shown'in T able" 1. i

Another advantagev of the helical knifecutting apparatus of this 'inventionis the-large production rate which can be achieved even when cutting relatively' short lengths" of staple fibers, e. g., .see the' comparison between-the centrifugally'fed and the helical cutter in Table 11.

Table ll Helical Centrifd CutterUsed Knife ganyfed M Length-Out inches. 1% 1% Total Tow Denier 2, 000,000 170,000 Throughput, ydsJmin; 143 Production, lbs./hr 1, 700 330 1 In the table the tow denieruwas taken.-as 2,000;000-..'! Actually, .thereappears' to be no obvious limit-to the numm ber of ends .which canhbe icut SIIIIUIIQIICQUSIY01131116). helicalJcutter sand it probably;depends only. onthe size-1 and eifectivenessof theiclampingjaws and thesizei'of: the knife-blades... In contrast,the.centrifugallytfed cuvter'v is limited bythe twist .imparted :tothe towoby the? rotationtof the.rotor. When largeztowsare used-the. outer. filaments. are 1 appreciably longen than-1 the .centerr: ones (one turnnper. cut)- when-.any. given tufthisiun-m twisted.:=-This becomes noticeable-tor tows in .:di-..-. ametenandvseriouswhen. cutting a millionaandxa half-1E denier.(%" dia. rope) a p In the preferred mode of operation for the --apparatus T. of thisinvention theispeedof the .clamp:chain-=is main-a: tained constant, e. g., 60 yds./min., as shown in Tablev; II, to simplify the:changes,.necessary whenngoing from the .cuttingof .one staple lengthQto-the cutting -.of' a dif-.;- ferent length .staple. l .Thu's,4when holdingihe speeduof this .clampchain..constant;..the stap1e-. .length dependsx only upon thepitch. of the helical; knifei.. The-.-forward-.= linear speed .at which any: -poi nt.on-the. helix of-.-the. -knifel advances must, of course, beequal to the'speed-of thet. clamp. chain and this.is achievedsbyausing..the.appropriatechange gears inspeed .reducer..20l 'so.as to mesh. the. .knife lwithathe. proper clamp. chain assembly. An-.. other particular. advantage -of the. .apparatustof thisin-t-- vention is the easy.-interchangeabiblityirwhich .permits" the changing. over fromonesstaple. lengthlto a different.- staplelength .in .a matterLofonly. a few-minutes... lTh'e'. cutterand conveyor sub-assemblies .caneasily be changed and properly located on the ;main base. Hard steel lo-- catmg'pads may be provided to precisely.-locate the'knifeil unit on the "base or the'clamp chain. sub-assemhlyl' on. its. t base; Hinged'swin'g 'boltsmay beused'to mak'e". the'..v units fast. Power may be delivered to the knife 'unlt" and to the chain unit through block-type or other suittable couplings which are quickly and easily separated by lifting apart. Both the knife and the chain subassemblies may be equipped with locating pads and pins which pre-position the mechanism so that they match with the proper couplings and mesh properly the one with the other.

As many different embodiments of the present invention may be made without departing from the spirit or the scope thereof, it is to be understood that the invention is not limited to the specific embodiments disclosed except to the extent as defined in the appended claims.

What is claimed is:

1. Apparatus for cutting a continuous filament bundle into staple of uniform length which comprises a helical knife cutter provided with a cutting edge having a helix pitch equal to the desired staple length, said helical cutter being mounted for rotation about the helix axis, driving means for rotating said cutter, a conveyor belt arranged to advance past said cutter along an adjacent straight path substantially parallel to said axis of rotation, a plurality of clamping members for holding a filament bundle mounted at uniform intervals along said belt in position for said cutting edge to pass between adjacent members during cutting of the filament bundle, said members having clamping jaws adapted to close on a filament bundle with a positive gripping pressure to hold the bundle together in position for cutting, clamp-actuating means for successively closing the jaws of said clamping members on a filament bundle as each member reaches a given point in the advance toward said cutter and for successively opening the jaws of said. clamping members as each member reaches a given point beyond said cutter, and driving means for advancing said belt in synchronism with rotation of said cutter so that a clamping member will remain at the same distance from the adjacent operating portion of said cutting edge during cutting of filaments held by that member.

2. Apparatus as defined in claim 1 in which each of said clamping members is adapted to hold a filament bundle between a movable spring-loaded finger and an opposing fixed jaw.

3. Apparatus as defined in claim 1 in which said cutter has a helical cutting edge of gradually increasing radius from the portion where cutting is initiated and is arranged to sever the filaments of an advancing bundle with a saw-like motion.

4. Apparatus as defined in claim 1 in which said driving means operate to advance said belt and to rotate said cutter continuously to provide for continuous cutting of filaments into staple.

5. Apparatus as defined in claim 1 in which said clamp-actuating means comprises cam followers attached to movable portions of each of said clamping members, each of said arms being movable to open the jaws of the clamping member against the action of a spring, and a cam surface arranged to press against said arms to open the jaws for releasing cut staple, and arranged to release said arms when the jaws are again in position to grip the filament bundle being fed to the cutter.

6. Apparatus for cutting a continuous filament bundle into staple of uniform length which comprises a rotatable knife cutter having a helical cutting edge of gradually increasing radius and a pitch equal to the length of staple to be cut, conveyor means for transporting a filament bundle along a path substantially parallel to the axis of rotation of said cutter in position to be cut when said cutter is rotated said conveyor means including a plurality of filament clamping members provided with jaws shaped for gripping a filament bundle mounted at uniform intervals along said conveyor corresponding to the pitch of said cutting edge, driving means for advancing said conveyor and rotating said cutter in proper synchronism to sever filaments between said clamping members, cam-actuated means for holding said jaws open at positions removed from the cutter, and spring-actuated means for closing said jaws while in proximity to the cutter to grip a filament bundle during severing of the filaments by the cutter.

7. In an apparatus for cutting a continuous filament bundle into staple, the combination of a rotatable knife cutter having a helical cutting edge, a conveyor belt passing through a path substantially parallel to the axis of rotation of said cutter and adjacent to said cutting edge, a plurality of filament clamping members provided with jaws adapted to close on and grip a filament bundle mounted at uniform intervals along said belt in position to hold a filament bundle against said cutting edge, clampactuating means for closing said jaws on a filament bundle prior to the cutter and for opening the jaws after the cutter to release the cut filaments, and driving means for rotating said cutter and moving said belt past the cutter in proper synchronism to feed a filament bundle continuously to the cutter, cut the filaments into staple, and release the cut staple.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,510,729 Weisner Oct. 7, 1924 2,187,791 Lipps Jan. 23, 1940 2,547,157 Gibbons Apr. 3, 1951 FOREIGN PATENTS Number Country Date 639,466 Great Britain June 28, 1950 

